Buy now button

On a web site we need to add a "Buy Now" button that redirects to paypal and asks to confirm a paid subscription. In the button HTML code we have to be able to set the following data (since there will be different buttons) : 1) Price for first X days will be [login to view URL] CURRENCY 2) After the first X days the price will be [login to view URL] CURRENCT every : 1 month, 3 months, 6 months, 12 months (recurring charge) 3) CURRENCY 4) Tax (percentage) The buttons are to be done in a way that no one can hack the amount or the data After the user clicks gets redirected to paypal payment and after the payment is confirmed the user should be redirected automatically to a registration page. On the above page we should : a) add a captcha, b) a field for the password confirmation and check that the password has good strenght, c) remove username since we will use the email as username, d) check that the email is correct and not in use. After the registration is made we should save the data on DB and set the login expire date according with paypal/plan duration In case the payment is not confirmed/cancelled we should send an email advising that a registration request was cancelled telling the user email The plans has to be renewed automatically, in case the user cancel the plan or doesn't renew we have to get an email and set the user on the db as inactive. At renewal we should automatically update the plan duration on the db We will also need to have another button to manage the plan duration